electrochemically-mediated separations for co capture

Page | 1

Electrochemically-Mediated Separations for CO2 Capture

Fritz Simeon, Mike Stern, Howard Herzog and T. Alan Hatton

Department of Chemical Engineering and the MIT Energy Initiative (MITei)Massachusetts Institute of Technology

Cambridge, MA 02139, USA

Page | 2

Carbon Capture and MitigationCCCCCCCaaaaaaarrrrrrrbbbbbbbooooooonnnnnnn CCCCCCCaaaaaaappppppptttttttuuuuuurrrrrrreeeeeee aaaaaaannnnnnnddddddd MMMMMMiiiiiitttttttiiiiiigggggggaaaaaaatttttttiiiiiiiooooooonnnnnnnCoal to play a major role in world’s energy future:

lowest-cost for base-load electricity generationcoal resources distributed around the world.

Adverse environmental effects accompany its mining, transport and utilizations.Carbon Capture and Storage (CCS

mitigate contribution of carbon-based fuel emissions to climate change, capture carbon dioxide (CO2) from point sources, e.g., power plants and other industrial facilities, and store it in deep subsurface geological formations for indefinite isolation from the atmosphere.

http://www.tobacco-facts.net/2009/12/coal-will-be-harder-to-quit-than-tobacco

World Electricity Generation by Fuel, 2005-2030

Trillion Kilowatt-hours

Sources: 2005: Energy Information Administration (EIA), International Energy Annual 2005 (June-October 2007), website www.eia.doe.gov/iea. Projections: EIA, System for the Analysis of Global Energy Markets/Global Electricity Module (2006).

Sources: 2005: Energy Information Administration (EIA) International Energy Annual 2005 (June

Petawatt-hours (1015 watt-hours)

Sources: 2005: Energy Information Administration (EIA), International Energy Outlook 2005, website www.eia.doe.gov/iea.

World Primary Energy Consumption,2005-2025

Coal Combustion Capture TechnologyCCCCCCoooooooaaaaaaalllll CCCCCCCooooooommmmmmmbbbbbbuuuuuusssssstttttttiiiiiiooooooonnnnnnn CCCCCCCaaaaaappppppttttttuuuuuurrrrrreeeeee TTTTTTTeeeeeeeccccccchhhhhhnnnnnnnoooooolllllooooooggggggyyyyyyy

Page | 3

Coal

Power & Heat

Air

Power & Heat

Power & Heat

Air Separation UnitAir

A

r &

O2

P

P

Reformer &CO2 Separator P

Air

CO2 CaptureUnit

CFlue Gas

H2CO2

Compression/Dehydration

H CO

DehydraSequestration

CO2

CO2

CO2

N2

N2, O2

Post-Combustion

Pre-Combustion

Oxy-Combustion

Pre-combustion Challenges:Low operational temperature of existing CO2removal technology.More economical to combust syngas before fully shift (reducing fraction of CO2 captured).

Oxy-combustion Challenges:Expensive cryogenic air separation.High operational temperature of pure oxy combustion requires new materials for boiler.

H2

Post-combustion Challenges:Dilute CO2 concentration in flue gas.Other flue gas components.High capital and operational costs.

Page | 4

Gas Separation Technology for Post-Combustion CCS

Absorption

Reactive Solid

AdsorptionMembrane

Biological Exploratory Adsorption

orp

tive

Ae

Excal

Flue Gas R&D Pathways

Alkanolamines, Blended alkanolaminesPiperazine, Amino acids

Second generation amineThird generation sorbent,

Potassium carbonate, Chilled ammonia

Gas/liquid contractorsPermselective membranesHigh-temperature polymeric

ZeolitesCarbonSilica

Alumina

Metal OxidesSodium BicarbonateSodium HydroxideLithium ZirconateLithium Silicate

Algae (photosynthesis)

Carbonic anhydrase(enzyme-catalyzed CO2 capture)

Metal Organic FrameworksCO2 HydratesLiquid crystalsIonic Liquids

Thermal-Swing Processes

Isothermal ProcessesPressure-Swing Processes Electrochemical-Swing Processes

Energy for Separation

Page | 5

Gas Separation Technology for Post-Combustion CCS

Energy for Separation

Thermal-Swing Processes

Isothermal ProcessesPressure-Swing Processes Electrochemical-Swing Processes

Absorption

Reactive Solid

AdsorptionMembrane

Biological Exploratory Adsorption

orp

tive

Ae

Excal

Flue Gas R&D Pathways

Excellent CO2 selectivity over N2Reduce capital & operational costs

Lower energy consumedMinimize oxidative degradation

Minimize Sox & Nox degradations

Increase CO2 permeation ratesIncrease selectivity

Improve economies of scale

Increase CO2/N2 selectivityIncrease CO2 capacity

Required highly porous materialsImprove long term stability

Improve long term performance

Challenge in economies of scaleLong term biological activity/stability

Increase CO2 capacityImprove CO2 selectivity

Objective of CCS R&D of DOE in The United of StatesOOOOOOObbbbbbbjjjjjjjeeeeeeeccccccctttttttiiiiiivvvvvveeeeeee ooooooofffffff CCCCCCCCCCCCCCSSSSSSS RRRRRR&&&&&&&DDDDDDD ooooooofffffff DDDDDDDOOOOOOOEEEEEE iiiiiiinnnnnnn TTTTTThhhhhhheeeeeee UUUUUUUnnnnnnniiiiiiittttttteeeeeeeddddddd ooooooofffffff SSSSSSStttttttaaaaaaattttttteeeeeeesssssss

Page | 6

CCS technology requires new approachesto achieve target of 35% maximum increase in COE.

Minimum CO2 capture = 90%Maximum increase in COE = 35%

“Energy Cost + Retrofitting Cost”

“Capital C

ost + Operational C

ost”

DOE/NETL-2009/1366 – Existing Plants, Emissions and Capture – Setting CO2 Program Goals

Traditional Wet-Scrubbing ProcessTTTTTTTrrrrrrraaaaaaadddddddiiiiiiitttttttiiiiiioooooonnnnnnaaaaaallllll WWWWWWWeeeeeeeeeeeetttttt Scccccccrrrrrruuuuubbbbbbbbbbbiiiiiiinnnnnnnggggggg PPPPPPPrrrrrrroooooocccccceeeeeessssssssssssssSSSSSSttttttt-----SSSSSSS

Developed over 70 years ago as non-selective acid gas removal processesToday, the only real option for deploying CCS technologyRecent solvent R&D focuses on solvent degradation and equipment corrosionNeed significant improvement to meet 35% maximum increase in COE

Page | 7

Rochelle, G. T., Science 2009, 325:1652-1654

The theoretical minimum work is 0.11 MWh/ton CO2

With extensive energy integration,

Potential Benefit of Electrochemical-Swing ProcessesPPPPPPooooooottttttteeeeeeennnnnnntttttttiiiiiiiaaaaaallllll BBBBBBBeeeeeeennnnnnneeeeeeefffffffiiiiiiittttttt oooooooffffff EEEEEElllllleeeeeeeccccccctttttttrrrrrrroooooooccccccchhhhhhheeeeeeemmmmmmmiiiiiiicccccccaaaaaaaaaaaaaa Swwwwwwwiiiiiinnnnnnnggggggg PPPPPPrrrrrrooooooocccccceeeeeeesssssssssssssseeeeeeesssssssSSSSSSlllll-----SSSSSSS

Significant decrease in total energy consumption for CCSEase of integration with existing power plants

Decrease in indirect cost of CCSApplicable to other large-scale carbon emitters with no possibility for energy integration for thermal swing processes

Cement and chemical industries

Page | 8

Electrochemical Separation ProcessesEEEEEEllllllleeeeeeeccccccctttttttrrrrrrooooooocccccchhhhhheeeeeemmmmmmiiiiiicccccccaaaaaaalllll SSSSSSSeeeeeeppppppaaaaaarrrrrraaaaaaatttttttiiiiiiooooooonnnnnnn PPPPPPPrrrrrroooooocccccceeeeeesssssssssssssseeeeeeesssssssAdvantages of electrochemical processes in waste treatment industry:

VersatileEnergy efficient

Lower temperature requirementsCell optimization to minimize power losses caused by overpotential and side reactions

Cost effective

Page | 9

Electrochemical-Swing Gas Separation Technologies

Electrochemical Reactionof Target Molecules

Electrochemical Reactionof Carrier Molecules

Mode 1

OxOxinflux outflux

Ox ne Red Red Ox ne

Red Ox

Re

x

ed

Mode 2

AAinflux outflux

Ox ne RedA Red A Red

Red Ox neA -Red A Red

A-Red A

A -Red

Page | 10

Electrochemical Separation Processes

1970 – Electrochemical pumping of NO through thin films (Mode 2)

1981 – Flue gas desulfurization using an electrochemical SO2 concentrator(Mode 1)

1974 – Molten carbonate electrochemical CO2 concentrator (Mode 1)

1979 – Aqueous carbonate electrochemical CO2 concentrator(Mode 2)

1984 – Electrochemical removal and concentration of H2S from coal gas(Mode 1)

Electrochemically-modulated complexation: CO concentrator – 1995(Mode 2)

Electrochemically-modulated complexation: CO2 air capture – 2003(Mode 2)

Electrochemically-modulated complexation: ethylene/ethane separator – 1997(Mode 2)

Separation of CO2 from flue gas using electrochemical cells – 2010(Mode 2)

Electrochemical heterocyclic nitrogen compound separation – 1993(Mode 2)

Electrochemical Swing Gas Separation ProcessesEEEEEEllllllleeeeeeeccccccctttttttrrrrrrroooooooccccccchhhhhheeeeeeemmmmmmiiiiiicccccccaaaaaaalllllll SSSSSSSwwwwwwwiiiiiinnnnnnggggggg GGGGGGaaaaaaasssssss SSSSSSSeeeeeeeppppppaaaaaarrrrraaaaaattttttiiiiiiooooooonnnnnnn PPPPPPPrrrrrrrooooooocccccceeeeeesssssssssssssseeeeeeesssssss

Page | 11




Mode 1

OxOxinflux outflux

Ox ne Red Red Ox ne

Red Ox

Re

x

ed

Mode 2

AAinflux outflux

A-Red

Molten Carbonate Electrochemical Cell (1974)Considered for CO2 removal in a manned spacecraftElectrochemical reactions:

Cathodic reaction: CO2 + ½O2 + 2e = CO32-

Anodic reaction: CO32- = CO2 + ½O2 + 2e

High temperature operation ~ 700°C60% CO2 removal efficiencyCO2 removal efficiency increases with increasing current densityCurrent efficiency decreases with increasing applied current density(still remaining challenge)

Page | 12

Electrochemical Gas Separation of CO2

Molten Carbonate Fuel Cell(Hydrogen Mode)

Molten Carbonate CO2 Separation Cell(Driven/Nitrogen Mode)

H2

CO2-AIR CO2-AIR

H2H2OCOCO2

CO2-AIR CO2-AIR

N2N2CO2

PorousElectrodes

PorousElectrodes

CO2 + ½O2 + 2e � CO32-

CO2 + ½O2 + 2e � CO32-

CO32- � CO2 + ½O2 + 2e

CO2 + H2 � CO + H2OCO3

2- � CO2 + ½O2 + 2e

Winnick, J. et al., AIChE Journal 1982, 28(1):103-111

FGD using electrochemical SO2 concentrator (1981)Electrochemical reactions:

“Driven” mode:Cathode: SO2 + O2 + 2e = SO4

2-

Anode: SO42- = SO3 + ½O2 + 2e

“Reducing-gas” mode:Cathode: SO2 + O2 + 2e = SO4

2-

Anode: SO42- + 5H2 = 4H2O + H2S + 2e

Page | 13

Electrochemical Gas Separation

Cell configuration for electrochemical SO2 concentrator

Townley, D. and Winnick, J. Ind. Eng. Chem. Process. Des. Dev. 1981, 20(3):435-440

FGD using electrochemical SO2 concentrator (1981)Electrochemical reactions:

“Driven” mode:Cathode: SO2 + O2 + 2e = SO4

2-

Anode: SO42- = SO3 + ½O2 + 2e

“Reducing-gas” mode:Cathode: SO2 + O2 + 2e = SO4

2-

Anode: SO42- + 5H2 = 4H2O + H2S + 2e

Operational condition:Concentrate SO2 from 0.03% at the cathode to 10% at the anode at 600°C.

Operational energy costs:For a 500 MWe plant burning 3.5% sulfur coal of 9000 Btu lb heating value, the total electrical energy required is about 2% of the plant power, comparing to other FGD processes requiring up to 6% of plant power.

Operating costs:~ 0.05 cents/kWh in the driven mode and ~ 0.15 cents/kWh in the reducing-gas mode (wet scrubbing processes cost 0.14 to 0.20 cents/kWh).

Experimental result:Nearly all SO2 was scrubbed from the flue gas, with less than 5 ppm remained.

Page | 14


Cell configuration for electrochemical SO2 concentrator

Townley, D. and Winnick, J. Ind. Eng. Chem. Process. Des. Dev. 1981, 20(3):435-440

Electrochemical Gas SeparationElectrochemical removal of H2S from coal gas (1984)

Electrochemical reactions:Cathode: H2S + 2e = H2 + S2–

Anode: S2– = ½ S2 + 2e Feasible H2S removal at high temperature98% removal efficiency of H2S withreasonable levels of polarizationFavorable capital and operational costs for the H2S concentrator

Page | 15

Removal efficiency as a function of current density Current efficiency as a function of current density at 840°C and 65% H2S cathode inlet

Current Sources

ElectrolyteMembrane

Porous Cathode

Porous Anode

H2S Contaminate

d Fuel Gas

Polished Fuel Gas

Sweep N2S2 Vapor

Sweep N2

H2S

H2

S2

Current Density (mA/cm2)C

urre

nt E

ffici

ency

Rem

oval

Effi

cien

cy

Current Density (mA/cm2)

Lim, H. S. and Winnick, J. J. Electrochem. Soc. 1984, 131(3):562-568

Electrochemical Swing Gas Separation ProcessesEEEEEEllllllleeeeeeeccccccctttttttrrrrrrroooooooccccccchhhhhhheeeeeeemmmmmmmiiiiiiicccccccaaaaaaalllllll SSSSSSSwwwwwwwiiiiiiinnnnnnggggggg GGGGGGGaaaaaaasssssss SSSSSSSeeeeeeepppppppaaaaaaarrrrrraaaaaaatttttttiiiiiiooooooonnnnnnn PPPPPPPrrrrrrroooooooccccccceeeeeeesssssssssssssseeeeeeesssssss

Page | 16




Electrochemical Facilitated Transport Processes Equilibrium Stage Processes

Electrode

Electrodedd

El t d

Feed Stream

Receiving Stream

Step 1:Increase Carrier Affinity

Step 3:Decrease

Carrier Affinity

Step 4:Solute

Stripping

Step 2:Solute

ExtractionFeed Stream

Receiving Stream

Electrode Electrode

Electrochemical Activation

Electrochemical Deactivation

Target Capture

TargetRecovery

Carrier Regenerationn

Electrically Induced Carrier Transport (1970)(Electrochemical Facilitated Transport Processes)

Redox carrier, ferrous chloride, facilitates electrochemical pumping of nitric oxide (NO) through thin films creating a pressure difference in the NO

Page | 17


Concentration profile in a liquid film across

Concentration profiles which are established due to passage of current through the film

Induced transport of nitric oxide as a function of current density

Liquid Film

NONOinflux outflux

Fe3 e Fe2

NO Fe2 FeNO2 FeNO2 NO Fe3 e

FeNO2+

Cathodic reaction:

Anodic reaction:

Ward, W. J. Nature 1970, 227:162-163

Electrochemically-Regenerable CO2 Absorber (1979)(Electrochemical Facilitated Transport Processes)

Overall reactions: CO32– + H2O + Electrical Energy = 2OH– + CO2 + Heat

Separation of CO2 from flue gas using electrochemical cells (2010)Electrochemical reactions:

Cathode reaction: O2 + 2H2O + 4e = 4OH–

Anode reaction: 4OH– = O2 + 2H2O + 4e

Page | 18

Electrochemical Gas Separation of CO2

2H2O

2OH–

H2

CO2

+ CO32–

H2

CO2

CO32–

H2O

External Gas Manifold

Cathode Anode

Process Gas Inlet

Process Gas Outlet

2H2O 2e 2OH H2 CO32 H2 H2O CO2 2e

Life System, Inc. 1973, Electrochemical CO2 Concentrator

Pennline, H.W. et al Fuel 2010, 89:1307-1314

Requirements for redox active carriers:Carrier soluble only in contacting phaseCarrier with target binding site and ability to undergo chemically reversible redox cycle in presence and absence of target moleculeConsiderable differences in the affinity of carrier for target molecule in different oxidation statesRapid kinetics of complexation reaction

Applications:Heterocyclic nitrogen compound separation (1993)

Fe(II) and Fe(III) electrochemical cyclingContinuous electrochemically-modulated complexation separation process

Carbon monoxide separation (1995)Cu(I) and Cu(II) electrochemical cycling

Ethylene/Ethane separation (1997)Cu(I) and Cu(II) electrochemical cycling

Air capture of carbon dioxide (2003)2,6-di-tert-butyl-1,4-benzoquinone electrochemical cycling

Page | 19

Equilibrium Staged Electrochemical Separations

Jemaa, N. et al. AIChE Journal 1993, 39(5):867-875

Terry, P. A. et al. AIChE Journal 1995, 41(12):2556-2564

Terry, P.A. et al. AIChE Journal 1997, 43(7):1709-1716

Scovazzo, P. et al. J. Electrochem. Soc. 2003, 150(5):D91-D98

Electrochemical Separation ProcessesEEEEEEllllllleeeeeeeccccccctttttttrrrrrrroooooooccccccchhhhhhheeeeeeemmmmmmmiiiiiicccccccaaaaaaallllll SSSSSSSeeeeeeepppppppaaaaaarrrrrraaaaaaatttttttiiiiiiooooooonnnnnnn PPPPPPPrrrrrrooooooocccccceeeeeeesssssssssssssseeeeeeesssssssPotential-swing induces dramatic change in effective binding constant of carrier (C) toward target molecule (L)

Ability to control binding constant (Kbinding)Can approach thermodynamically-reversible separation with potential-swing processes

Page | 20

0.0001

0.001

0.01

0.1

1

10

100

1000

10000

-0.30 -0.20 -0.10 0.00 0.10 0.20 0.30

E EoE

C ne C*

C* L C*L

Kbinding EE EEE Kbinding EoE

EEE expnFRT

Eo EERR

Kbinding EoEo [C L]

[C ][L]0.1 to 100 M 1

Page | 21

Ideal Work for Electrochemical Separation

Reaction during absorption process:

Reaction during desorption process:

Electrical energy required per mole of CO2 separated:

Separation UnitCO2 Rich Flue gasCleaned Flue Gas

Carbon Dioxide

Electrical Work

Welectrical F E

E Ecathode Eanode

C e C *C * CO2 C * CO2CO

C * CO2CO C CO2C CO e

C CO2C CO C CO2

Page | 22

Minimum Work of Electrochemical Separation

Nernst Equation:

Equilibrium of C* with CO2:

Extent of reaction with respect to CO2:

Electrical energy required per mole of CO2 separated:

E Eo RTnF

lnredrerroxooo

Eo RTF

lnC *CCC

KbindingC * CO2CCC

C *C CO2C

nCO2 ,o nCO2 ,t

nCO2 ,o

CredC C *C C * CO2CCC

CC T CC CredC

E EoRTF

lnCredC

CC T CredCC 1 Kbinding CO2C

CrC errC

1

Ecathode Ecapture0

1dd

Eanode Eregeneration0

1dd

Equilibrium Stage Processes(FOUR-STAGE PROCESSES)

Electrode

Electrode

Feed Stream

Receiving Stream

Step 1:Increase Carrier Affinity

Step 3:Decrease

Carrier Affinity

Step 4:Solute

Stripping

Step 2:Solute

Extraction

Electrochemical Facilitated Transport Processes(TWO-STAGE PROCESSES)

Feed Stream

Receiving Stream

Electrode Electrode



Target Capture

TargetRegeneration

Carrier Regeneration

Electrochemical Facilitated Transport Processes(TWO-STAGE PROCESSES)

Feed Stream

Receiving eceivinStream

Electrode Electrode

ectrochemicleEl caal activationcAc

ectrochemicleEl caal aDeactivatiooono

Target argetCapture

TargetTontitRegenerat

Carrier nooRegeneration

Equilibrium Stage Processes(FOUR-STAGE PROCESSES)

Electrode

Electrodedd

El t d

Feed Stream

Receivingg Stream

Step 1:Increasee Carrier Affinity

Step 3:Decrease D

Carrier Affinity

Step 4:Solute

Stripping

Step 2:Solute

Extractionnn

Minimum Work of Electrochemical Separation

Page | 23

Four-Stage Processes:(Electrochemical Separation)

Two-Stage Processes:(Electrochemical Separation)

Welectrical RT ln KbindingPCO2 ,regeneration

VmHCO2

KKK

Welectrical RT ln xCO2

o 1 xCO2

o

xCO2

o ln 1 xCO2

o1lll

100

1000

10000

100000

0.1 0.3 0.5 0.7 0.9

3 8 13 18

Minimum Work for Electrochemical Separation

Page | 24

Two Stage Process

Four Stage Process

LOG(Kbinding)

CO2 partial pressure at the inlet stream (atm)

Min

imum

wor

k fo

r sep

arat

ion

(J p

er m

ole

of C

O2)


o 1 xCO2

o

xCO2

o ln 1 xCO2

o1lll

Welectrical WCO2 separation


VmHCO2

KKK

Final CO2 Partial Pressure = 1 atmCO2 solubility = 0.129 mol/L atm

100

1000

10000

100000

0.1 0.3 0.5 0.7 0.9

3 8 13 18

Minimum Work for Electrochemical Separation

Page | 25

Two Stage Process

Four Stage Process

LOG(Kbinding)

CO2 partial pressure at the inlet stream (atm)

Min

imum

wor

k fo

r sep

arat

ion

(J p

er m

ole

of C

O2)

Final CO2 Partial Pressure = 1 atmCO2 solubility = 0.129 mol/L atm


VmHCO2


o 1 xCO2

o

xCO2

o ln 1 xCO2

o11llll

Welectrical WCO2 separation

Page | 26

Two Stage Electrochemical Separation Process

CO2 Rich Flue Gas

Cleaned Stack Gas

Pure CO2 Stream

Electrode Electrode



CO2 Capture

CO2Regeneration

Carrier Regeneration

Sorbent PhaseSorbent Phase Gas PhaseGas Phase

Absorption Process Desorption Process

C

C*

C* C*

C

C

CO2 capture and regeneration processes mediated by simultaneous activation and deactivation of redox carriers through electrochemical processes.

Redox Carrier for CO2 Capture RRRRRRReeeeeeedddddddoooooooxxxxxx CCCCCCaaaaaarrrrrrrrrrrrriiiiiiieeeeeeerrrrrr fffffffoooooorrrrr CCCCCCOOOOOOOOOOOOO222222 CCCCCCaaaaaappppppptttttttuuuuuuurrrrrrreeeeeee CCCCCCC2222222

Page | 27

Acid-base reaction of dianionic quinones with CO2 - electron rich oxygens donate and

share electron pairs with electrophiliccarbon of CO2 molecules to form stable

carbonates

Ni(II) complexes2Cu(II) complexes1

Metal Organic Carrier

2,6-di-tert-butyl-1,4-benzoquinone3

Organic Carriers

CO2

CO2

2e–

2e–

reduction

captureoxidation

regeneration

QUINONE

High Electron Density Low Electron Density

red

– oxidation capture

on

1Appel, A.M. .et al. Inorganic Chemistry 2005, 44(9):3046-30562Newell, R. et al. Inorganic Chemistry 2005, 44(2):365-3733Scovazzo, P. et al. J. Electrochem. Soc. 2003, 150(5):D91-D98

Electrochemistry – Cyclic Voltammetry TechniqueEEEEEEllllllleeeeeeeccccccctttttttrrrrrrroooooooccccccchhhhhhheeeeeeemmmmmmmiiiiiissssssstttttttrrrrrrryyyyyyyyyyyyy ––––––– CCCCCCCyyyyyyccccccllllllliiiiiiccccccc VVVVVVVooooooolllllltttttttaaaaaammmmmmmmmmmmmmeeeeeeetttttttrrrrrrryyyyyyy TTTTTTeeeeeeeccccccchhhhhhhnnnnnnniiiiiiiqqqqqqquuuuuuueeeeeeeCCCCCCC––––

Page | 28

Lowest UnoccupiedMolecular Orbital

Oxidized CarrierMolecular Orbital

Reduced CarrierMolecular Orbital

Highest OccupiedMolecular Orbital

Fermi Level

Fermi Level

Electrode

Electrode

e

e

Reduction

Oxidation

Study electrochemistry of carrier by monitoring electron flowing from the electrode (reduction) and to the electrode (oxidation).

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

-6

-4

-2

0

2

4

6

8

10

-1 4 9 14

Cur

rent

((A)

Pot

entia

l (V

)

Time (s)

Oxidation

Reduction

-6

-4

-2

0

2

4

6

8

10

0 0.2 0.4 0.6 0.8Cur

rent

( 2(A)

Potential (V)

Oxidation

Reduction

Electrochemistry of 2,6-dichloro-quinone (BQ-Cl2)EEEEEEllllllleeeeeeeccccccctttttttrrrrrrooooooocccccchhhhhheeeeeemmmmmmiiiiiissssssstttttttrrrrrryyyyyyy oooooooffffff 222222,,,,,666666 iiiiiiicccccchhhhhhhllllllooooooorrrrrrrddddddd666666-------ddddddd rrooooooo uuuuuuuiiiiiiinnnnnnnooooooonnnnnneeeeeee ((((((BBBBBBBQQQQQQQqqqqqqooooooo-------qqqqqq QQQQQQQ CCCCllll2222222)))))))CCCCCCCQQQQQQQ-------CCCCCCC

Page | 29

-60

-50

-40

-30

-20

-10

0

10-2.5-2-1.5-1-0.50

Cur

rent

(

-2(A

)Potential (V)

under Nitrogen

-60

-50

-40

-30

-20

-10

0

10-2.5-2-1.5-1-0.50

Cur

rent

(

-(A

)

Potential (V)

under Carbon Dioxide

-0.85 V1st electron transfer

-1.66 V2nd electron transfer



CO2 stabilizes the dianion quinone

BQ-Cl2

Electrochemistry of 2,6-dichloro-quinone (BQ-Cl2)EEEEEEllllllleeeeeeeccccccctttttttrrrrrrroooooooccccccchhhhhhheeeeeeemmmmmmmiiiiiissssssstttttttrrrrrrryyyyyyy ooooooofffffff 2222222,,,,,6666666 iiiiiiiccccccchhhhhhhllllllooooooorrrrrrrddddddd6666666-------ddddddd rrooooooo uuuuuuuiiiiiiinnnnnnnooooooonnnnnnneeeeeee (((((((BBBBBBBQQQQQQQqqqqqqqooooooo-------qqqqqqq QQQQQQQ CCCCClllllll2222222)))))))CCCCCCCQQQQQQQ-------CCCCCCC

Page | 30

-60

-50

-40

-30

-20

-10

0

10-2.5-2-1.5-1-0.50

Cur

rent

(

-2(A

)

Potential (V)

under Nitrogen

-60

-50

-40

-30

-20

-10

0

10-2.5-2-1.5-1-0.50

Cur

rent

(

-(A

)

Potential (V)






CO2 stabilizes the dianion quinone

BQ-Cl2

Electrochemistry of 2,6-ditert-butyl-quinone (BQ-TB)EEEEEEllllllleeeeeeeccccccctttttttrrrrrrooooooocccccchhhhhheeeeeemmmmmmiiiiiissssssstttttttrrrrrryyyyyyy oooooooffffff 222222,,,,,666666 iiiiiiittttttteeeeeerrrrrrddddddd666666-------ddddddd rrrrrrttttt uuuuuutttttttyyyyyyybbbbbbbtttttt-----bbbbbb yyyyyy uuuuuuuiiiiiinnnnnnnooooooonnnnnneeeee ((((((BBBBBBQQQQQQqqqqqqqlllllll-------qqqqqqq QQQQQQ BBBBBB)))))))TTTQQQQQQ-------TTTTT

Page | 31

-60

-50

-40

-30

-20

-10

0

10-2.5-2-1.5-1-0.50

Cur

rent

(

-2(A

)Potential (V)

under Nitrogen

-60

-50

-40

-30

-20

-10

0

10-2.5-2-1.5-1-0.50

Cur

rent

( -(A

)

Potential (V)


BQ-TB

Two single electron transfer of BQ-TB under N2 One double electron transfer of BQ-TB under CO2

-1.19 V

-2.08 V

-1.12 V

1st electron transfer

2nd electron transfer

Electrochemical Reaction with Stack Gas ComponentsEEEEEEllllllleeeeeeeccccccctttttttrrrrrrroooooooccccccchhhhhhheeeeeeemmmmmmmiiiiiiicccccccaaaaaaalllllll RRRRRRReeeeeeeaaaaaaaccccccctttttttiiiiiiooooooonnnnnnn wwwwwwwiiiiiiittttttthhhhhhh SSSSSSStttttttaaaaaaaccccccckkkkkkk GGGGGGGaaaaaaasssssss CCCCCCCooooooommmmmmmpppppppooooooonnnnnnneeeeeeennnnnnntttttttsssssss

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From The Future of Coal, MIT, 2007, page 115

Electrochemical Reaction with Stack Gas ComponentsEEEEEEllllllleeeeeeecccccccttttttrrrrrrroooooooccccccchhhhhheeeeeeemmmmmmiiiiiicccccccaaaaaaalllllll RRRRRRReeeeeeeaaaaaacccccctttttttiiiiioooooonnnnnnn wwwwwwwiiiiiiittttttthhhhhhh SSSSSSttttttaaaaaaccccccckkkkkk GGGGGGGaaaaaaasssssss CCCCCCCoooooommmmmmppppppooooooonnnnnnneeeeeeennnnnnntttttttsssssss

Page | 33

-80

-60

-40

-20

0

20

40-2 -1.5 -1 -0.5 0

Cur

rent

(mA

)Potential (V)

Oxygen Oxygen and Carbon Dioxide

Chemical reaction between superoxide anion radical (O2

•–) and CO2.1

O2 + 2CO2 + 2e– → C2O62–

indicated by disappearance of oxidation peak of superoxide anion radical (O2

•–) in the presence of CO2.

-1.3 V is the maximum cathodic potential limit for

ideal redox carrierEo

oxygen = -1.3VReduction

Oxidation

Reversible electrochemistry

1Wadhawan J.D. et al. J. Phys. Chem. B 2001, 105, 10659-10668

Inductive Effect of Side Functional GroupsIIIIIInnnnnnnddddddduuuuuuuccccccctttttttiiiiiivvvvvvveeeeeee EEEEEEffffffffffffffeeeeeeecccccccttttttt ooooooofffffff SSSSSSSiiiiiiidddddddeeeeeee FFFFFFFuuuuuuunnnnnnnccccccctttttttiiiiiiiooooooonnnnnnnaaaaaallllll GGGGGGGrrrrrrrooooooouuuuuuupppppppsssssss

Page | 34

BQ

BQ-TB

BQ-Cl2

BQ-Cl4

NQ

NQ-Cl2

AQ

PQunder nitrogenunder carbon dioxide

Reduction of O2

BQ BQ-TB BQ-Cl4

BQ-Cl2 NQ-Cl2NQ

AQ PQ

NO2 > F > COOH > Cl > Br > I > OH > OR > C6H5 > H > Me3C- > Me2CH- > MeCH2- > CH3

Electron-withdrawing Electron-donating

Inductive effect - transmission of charge through a chain of atoms by electrostatic induction.

-20

-15

-10

-5

0

5

10

15

-2.2 -1.4 -0.6 0.2C

urre

nt ((

A)

Potential (V)

-25

-20

-15

-10

-5

0

5

10

15

-2.2 -1.4 -0.6 0.2

Cur

rent

((A)

Potential (V)

Cyclic Voltammograms of Quinoidal Redox CarriersCCCCCCCyyyyyyyccccccclllllliiiiiiccccccc VVVooooooolllllltttttttaaaaaammmmmmmmmmmmooooooogggggggrrrrrraaaaaammmmmmmsssssssccccccc VVVVVVV oooooosssssss ooooooo QQQQQuuuuuuuiiiiiiinnnnnnooooooiiiiiiddddddaaaaaaaffffff QQQQQQQ RRRRRRReeeeeeedddddddoooooooxxxxxxallll RRRRRR CCCCCCCaaaaaaarrrrrrrrrrrrrriiiiiiieeeeeeerrrrrrrssssssxxxxxxx CCCCCCC

Page | 35

BQ

AQ

Reduction

Reduction

Oxidation

Oxidation

Internal Standard

Internal Standard

Ideal redox carrier must have “Nernstian” reversible electrochemistry

in the presence and absence of CO2

� Irreversible electrochemistry� Cathodic potential > -1.3V

(NOT IDEAL CARRIER)

� Reversible electrochemistry� Cathodic potential < -1.3V

(NOT IDEAL CARRIER)

Molecularly-Optimized Redox Carrier for CO2 CaptureMMMMMMMooooooollllllleeeeeeecccccccuuuuuuulllllaaaaaaarrrrrrrllllllyyyyyy OOOppppppptttttttiiiiiimmmmmmmiiiiiizzzzzzzeeeeeeedddddddOOOOOOOyyyyyy-------OOOOOOO RReeeeeeedddddddoooooooxxxxxxdddddd RRRRRRR CCCCCCCaaaaaaarrrrrrrrrrrriiiiiieeeeeeerrrrrrr fffffffooooooorrrrrrr CCCCCCCOOOOOOOxxxxxxx CCCCCCC OOOOOOO22222 CCCCCCCaaaaaaapppppppttttttuuuuuuurrrrrrreeeeeeeCCCCCCC2222222

Page | 36

-20

-15

-10

-5

0

5

10

15

-2.2 -1.7 -1.2 -0.7 -0.2 0.3

Cur

rent

((A

)

Potential (V)

0.00 CO2

0.10 CO2

0.20 CO2

0.40 CO2

0.60 CO2

0.80 CO2

1.00 CO2

reduction

oxidation

Internal standard

Under N2(0.00 CO2)

Increase CO2partial pressure

Eooxygen = -1.3V

� Reversible electrochemistry� Cathodic potential > -1.3V

(IDEAL CARRIER)

Concluding RemarksCCCCCCooooooonnnnnnncccccccllllllluuuuuuudddddddiiiiiinnnnnngggggg RRRRRRReeeeeeemmmmmmmaaaaaaarrrrrrkkkkksssssssElectrochemical separations have a potential for long-term CO2scrubbing applicationsTwo-stage electrochemical separator is ideal system for energy efficient CO2 capture processesFuture electrochemical CO2 separations:

Molecular-engineered redox carrier moleculeUnderstanding of electrochemical separationAdvanced infrastructure materials

Page | 37

Page | 38

COE of ECMS ProcessesCCCCCCCOOOOOOOEEEEEEE ooooooofffffff EEEEEEECCCCCCCMMMMMMMSSSSSSS PPPPPPPrrrrrrroooooooccccccceeeeeeesssssssssssssseeeeeeesssssss

0 5 10 15 20 25 30 35 40 45 50 55 60

5

10

15

20

25

30

35

40

45

50

55

60

Indirect Costs of CCS

Dire

ct C

osts

of C

CS Minimum lost

work due to CCS

ECMS

“Energy Cost + Retrofitting Cost”

“Capital C

ost + Operational C

ost”

Infeasible Region

New PC Plant

Phase I

Phas

e II

Material DevelopmentProcess Optimization

ExistingPC Plant

“Zero” Cost of Retrofitting to Existing Plant

PC P lant PC PlantPPPC PPAmine-Scrubbing Process

50% desorption efficiency70% compression efficiency

Process Development

AcknowledgementsAAAAAAAccccccckkkkkkknnnnnnnooooooowwwwwwwlllllleeeeeedddddddggggggeeeeeeemmmmmmmeeeeeeennnnnnntttttttsssssss

Funding

Siemens CorporationAs of today (assuming the contract will been signed), ARPA-E

Doing the Work

Fritz Simeon, Mike Stern and Howard Herzog

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electrochemically-mediated separations for co capture

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